Tong Yin

Influence of CYP2C9 and VKORC1 genotypes on the risk of hemorrhagic complications in warfarin-treated patients: a systematic review and meta-analysis.

BACKGROUND The main challenge for warfarin anticoagulation is the risk for hemorrhagic complications. Although certain pharmacogenetic factors may explain the individual variabilities about the therapeutic warfarin dose requirement, the genetic factors to warfarin hemorrhagic complications due to over-anticoagulation are largely unknown. To interpret the potential role of warfarin-related genotypes on over-anticoagulation and hemorrhagic complications, we conducted a meta-analysis based on 22 published studies. METHODS A comprehensive search was applied to the reports on over-anticoagulation and hemorrhagic complications published prior to December 31, 2012 in PubMed and EMBASE. References were identified by strict inclusion and exclusion criteria, with additional information obtained by consulting with the authors of primary studies. The roles of genotypes in CYP2C9 and VKORC1 on over-anticoagulation (INR > 4) and hemorrhagic complications were analyzed by Revman 5.0.2 software. RESULTS A total of 6272 patients in 22 reports were included in the meta-analysis, including studies of 18 from Caucasians (3 from both Caucasian and African-American), 3 from Asians, and 1 from Brazilians. Compared to CYP2C9 wild genotype (CYP2C9*1), both CYP2C9*2 (rs 1799853, c. 430 C > T, p. Arg144Cys) and *3 (rs 1057910, c. 1075 A >C, p. Ile359Leu) confer significantly higher risk for warfarin over-anticoagulation and hemorrhagic complications. After stratification by CYP2C9 allele status, significantly higher risk for hemorrhagic complications was found only in carriers of at least 1 copy of CYP2C9*3 [For total hemorrhages: *1/*3 HR: 2.05 (1.36-3.10), p < 0.001; *3/*3 HR: 4.87 (1.38-17.14), p = 0.01; For major hemorrhages: *1/*3 HR: 2.43 (1.17-5.06), p = 0.02; *3/*3 HR: 4.81 (0.95-24.22), p = 0.06]. Furthermore, similar susceptibility of total hemorrhage by CYP2C9 genotypes was observed in Caucasians and Asians. After stratification by the occurrence time, both CYP2C9*2 and *3 are risk factors for over-anticoagulation within 30 days of warfarin treatment [*2 HR: 1.64 (1.11-2.43), p = 0.01; *3 HR: 2.48 (1.56-3.96), p < 0.001], and only CYP2C9*3 showed higher risk for over-anticoagulation after 30 days [HR: 1.86 (1.08-3.20), P = 0.03]. For VKORC1 c. -1639G > A (rs 9923231) genotypes, GA and AA contributed significantly higher risk for over-anticoagulation within 30 days [HR: 2.14 (1.75-2.62), p < 0.001], but not for over-anticoagulation after 30 days [HR:0.78 (0.46-1.33), p = 0.36]. No significant association was found between VKORC1 genotypes and hemorrhagic complications. CONCLUSIONS Both CYP2C9 and VKORC1 genotypes are associated with an increased risk for warfarin over-anticoagulation, with VKORC1 c. -1639G > A more sensitive early in the course of anticoagulation. CYP2C9*3 is the main genetic risk factor for warfarin hemorrhagic complications.

Genetic determinants of high on-treatment platelet reactivity in clopidogrel treated Chinese patients

INTRODUCTION Cytochrome P450 (CYP), ATP-binding cassette transporters (ABCB1), and paraoxonase-1 (PON1) play crucial roles in clopidogel absorption and bioactivation. Genetic polymorphisms in these genes have been associated with the variability of the response to clopidogrel, however their contribution to high on-treatment platelet reactivity (HPR) in clopidogrel treated Chinese patients is less known. MATERIALS AND METHODS Five-hundred Chinese-Han patients treated with clopidogrel for acute coronary syndrome (ACS) were consecutively recruited from the Department of Geriatric Cardiology, General Hospital of Chinese Peoples Liberation Army, from September 2010 to September 2012. We assessed the relations of CYP2C19*2 (rs4244285), CYP2C19*3 (rs4986893), CYP2C19*17 (rs12248560), PON1Q129R (rs662) and ABCB1C3435T (rs1045642) to the platelet aggregation after 5 days maintenance dose of clopidogrel administration, and the risk for HPR. The cutoff of HPR was defined as 20 μmol/L adenosine diphosphate (ADP)-induced platelet aggregation>50%. RESULTS Both CYP2C19*2 and *3 alleles were significantly associated with higher platelet aggregation after 5 days maintenance dose of clopidogrel administration (P<0.00001 and P=0.042, respectively). The platelet aggregation in carriers of at least one CYP2C19 loss-of-function allele (*2 or *3, accounted for 58% of the study population) was obviously higher than that in non-carriers (P<0.00001). Patients with the CYP2C19*2 allele had a higher risk of HPR than those with the CYP2C19 wild-type genotype [adjusted hazard ratio (HR), 1.56; 95% confidence interval(CI), 1.04-2.33, P=0.03]. The carriers of at least one CYP2C19 loss-of-function allele could also predict significantly greater risk of HPR compared with non-carriers (adjusted HR1.79,95% CI: 1.33-2.4,P=0.003). However, the carriage of CYP2C19*3 alone could not predict the risk of HPR significantly (adjusted HR, 1.5; 95% CI: 0.83-3, P=0.16). Significant relation of CYP2C19*17, PON1Q129R and ABCB1C3435T to the platelet aggregation was not found. CONCLUSION In clopidogrel treated Chinese patients with ACS, carriers of at least one CYP2C19 loss-of-function allele could predict greater risk of HPR, with the impact mainly attributing to CYP2C19*2. Neither ABCB1 nor PON1 genotype could influence the antiplatelet response of clopidogrel in the cohort of Chinese patients.

Comparative performance of warfarin pharmacogenetic algorithms in Chinese patients

INTRODUCTION Multiple warfarin pharmacogenetic algorithms have been confirmed to predict warfarin dose more accurately than clinical algorithm or the fixed-dose approach. However, their performance has never been objectively evaluated in patients under low intensity warfarin anticoagulation, which is optimal for prevention of thromboembolism in Asian patients. MATERIAL AND METHODS We sought to compare the performances of 8 eligible pharmacogenetic algorithms in a cohort of Chinese patients (n=282) under low intensity warfarin anticoagulation with target international normalized ratio (INR) ranged from 1.6 to 2.5. The performance of each algorithm was evaluated by calculating the percentage of patients whose predicted dose fell within 20% of their actual therapeutic dose (percentage within 20%), and the mean absolute error (MAE) between each predicted dose and actual stable dose. RESULTS In the entire cohort, the pharmacogenetic algorithms could predict warfarin dose with the average MAE of 0.87 ± 0.17 mg/day (0.73-1.17 mg/day), and the average percentage within 20% of 43.8% ± 8.1% (29.1% - 52.1%). By pairwise comparison, warfarin dose prediction was significantly more accurate with the algorithms derived from Asian patients (48.6% - 50.0%) than those from Caucasian patients (29.1% - 39.7%; odds ratio [OR]: 1.61-3.36, p ≤ 0.02). Algorithms with additional covariates of INR values or CYP4F2*3 performed better than those without the covariates (adding INR: OR: 1.71 (1.08-2.72), p =0.029; adding CYP4F2*3: OR: 2.67(1.41-5.05), p =0.004). When the patients were stratified according to the dose range, the algorithms from Caucasian and racially mixed populations tended to perform better in higher dose group (≥ 4.5mg/day), and algorithms from Asian populations performed better in intermediate dose group (1.5-4.5mg/day). None of the algorithms performed well in lower dose group (≤ 1.5mg/day). CONCLUSIONS No eligible pharmacogenetic algorithm could perform the best for all dosing range in the Chinese patients under low intensity warfarin anticoagulation. Construction of a refinement pharmacogenetic algorithm integrating 3 genotypes (CYP2C9, VKORC1 and CYP4F2) and INR data should be warranted to improve the warfarin dose prediction in such patients.

Clinical benefits of pharmacogenetic algorithm-based warfarin dosing: meta-analysis of randomized controlled trials

BACKGROUND Pharmacogenetic (PG) algorithms were proposed to predict warfarin therapeutic dose more accurately. However, the clinical efficacy of the strategy over the standard treatment was not consistently proven. METHODS We conducted a meta-analysis of the published randomized controlled trials (RCTs) comparing PG algorithm-based warfarin dosing (PG group) with clinical or standard protocols (STD group). The PUBMED, EMBASE, Cochrane Library and Web of Science databases were searched up to June 2014. RESULTS A total of 10 RCTs were retrieved for the meta-analysis with the inclusion of 2,601 participants. Primary analysis showed both major bleeding (2.65% versus 4.75%; RR: 0.57, 95% CI: 0.37- 0.90, P=0.02) and thromboembolic events (0.59% versus 1.88%; RR: 0.38, 95% CI: 0.17-0.85, P=0.02) were significantly lower in PG than in STD group. There was a trend towards increased percentage of time in therapeutic range (%TTR) [mean difference (MD): 4.65, 95% CI: 0.01- 9.29, P=0.05] in PG group, but no difference was observed for over-anticoagulation (INR>4). Subgroup analyses showed significant reduction of both major bleeding and thromboembolic events in PG group when the follow-up time was more than 1 month. After stratified by different PG algorithms, significant major bleeding reduction could be found in PG group when warfarin indication or co-medication of amiodarone was integrated in the algorithms. CONCLUSION PG algorithm-guided warfarin anticoagulation is beneficial for the reduction of both major bleeding and thromboembolic events compared with standard dosing strategy. The benefits may be prominent in patients with longer follow-up time, or guided by refined PG algorithms.

Effect of high-dose clopidogrel according to CYP2C19*2 genotype in patients undergoing percutaneous coronary intervention– a systematic review and meta-analysis

INTRODUCTION High-dose clopidogrel has been recommended to overcome clopidogrel non-responsiveness in patients undergoing percutaneous coronary intervention (PCI), especially those with CYP2C19 loss-of-function genotypes. However, there is controversy over the pharmacodynamics and clinical effects of the strategy. This meta-analysis was conducted to evaluate the antiplatelet effects of high-dose clopidogrel according to CYP2C19*2 alleles in patients undergoing PCI. METHODS Based on PubMed, Cochrane, and EMBASE prior to June 1st, 2014, a systematic review and meta-analysis was conducted to evaluate the antiplatelet effects of high-dose clopidogrel on platelet reactivity and clinical outcomes in PCI treated patients according to CYP2C19*2 genotypes. The reported outcomes including on-treatment platelet reactivity (OTPR), high on-treatment platelet reactivity (HTPR), major adverse cardiovascular events (MACE), stent thrombosis and composite cardiovascular events. RESULTS Nineteen studies involving 10,960 patients were included. After high-dose clopidogrel administration (600/900 mg loading dose and/or 150 mg/day maintenance dose), compared with non-carriers, carriers of CYP2C19*2 genotype had significantly increased OTPR (SMD for VASP assay: 0.69, 95% CI: 0.48-0.90, p = 4 × 10(-4); for VerifyNow P2Y12 assay: 0.70, 95% CI: 0.54-0.85, p < 10(-5); for LTA assay:0.58, 95% CI: 0.48-0.69, p = 4 × 10(-4)). The incidence rate of HTPR was higher in CYP2C19*2 carriers after high-dose clopidogrel treatment (RR: 1.21, 95% CI:1.05-1.39, p = 0.008 for cutoff PRI > 50% by VASP assay; RR: 1.69, 95% CI: 1.44-1.98, p < 1 × 10(-4) for cutoff PRU > 230 by VerifyNow P2Y12 assay). As for clinical outcomes, CYP2C19*2 was associated with higher risk for MACE (RR: 1.68, 95% CI: 1.19- 2.37, p = 0.003), stent thrombosis (RR: 1.75, 95% CI: 1.31-2.34, p = 0.0001), as well as composite cardiovascular events (RR: 1.82, 95% CI: 1.42- 2.34, p < 10(-5)) after treated by high-dose clopidogrel. CONCLUSION High-dose clopidogrel could not overcome the variability of clopidogrel antiplatelet effects between the CYP2C19 *2 carriers and non-carriers in patients treated with PCI.

Estimation of the warfarin dose with a pharmacogenetic refinement algorithm in Chinese patients mainly under low-intensity warfarin anticoagulation.

Pharmacogenetic (PG) dosing algorithms have been confirmed to predict warfarin therapeutic dose more accurately; however, most of them are based on standard intensity of warfarin anticoagulation, and their utility outside this range is limited. This study was designed to develop and validate a PG refinement algorithm in Chinese patients mainly under low-intensity warfarin anticoagulation. Consented Chinese-Han patients (n=310) under stable warfarin treatment were randomly divided into a derivation (n=207) and a validation cohort (n=103), with 83% and 80% of the patients under low-intensity anticoagulation, respectively. In the derivation cohort, a PG algorithm was constructed on the basis of genotypes (CYP2C9*3 and VKORC1-1639A/G) and clinical data. After integrating additional covariates of international normalised ratio (INR) values (INR on day 4 of therapy and target INR) and genotype of CYP4F2 (rs2108622), a PG refinement algorithm was established and explained 54% of warfarin dose variability. In the validation cohort, warfarin dose prediction was more accurate (p < 0.01) with the PG refinement algorithm than with the PG algorithm and the fixed dose approach (3 mg/day). In the entire cohort, the PG refinement algorithm could accurately identify larger proportions of patients with lower dose requirement (≤2 mg/day) and higher dose requirement (≥4 mg/day) than did the PG algorithm. In conclusion, PG refinement algorithm integrating early INR response and three genotypes (CYP2C9*3, VKORC1-1639A/G, CYP4F2 rs2108622) improves the accuracy of warfarin dose prediction in Chinese patients mainly under low-intensity anticoagulation.

PON1 Q192R genotype influences clopidogrel responsiveness by relative platelet inhibition instead of on-treatment platelet reactivity

BACKGROUND paraoxonase-1 (PON1) was recently identified as the crucial enzyme for clopidogrel bioactivation, with PON1 Q192R (rs662) polymorphism determining the clopidogel antiplatelet efficacy. However, subsequent studies showed controversies over the findings. This study aimed to evaluate the impact of PON1 Q192R in parallel to that of CYP2C19*2 (rs4244285) on clopidogrel responsiveness in a cohort of Chinese patients with unstable angina pectoris. MATERIAL AND METHODS One hundred and eighty Chinese-Han patients diagnosed with unstable angina pectoris and treated with clopidogrel were consecutively recruited. Clopidogrel responsiveness, measured by relative platelet inhibition {RI=[(pretreatment aggregation-posttreatment aggregation at 5days)/(pretreatment aggregation)] x100%}, was assessed in relation to PON1 Q192R and CYP2C19*2 genotypes. RI values were stratified into four quartiles, with patients in quartile 1 defined as individuals of clopidogrel non-responsiveness. The contributions of PON1 Q192R and CYP2C19*2 to on-treatment platelet reactivity (OTPR) at 5days maintenance dose of clopidogrel were also evaluated. RESULTS For PON1 Q192R genotypes, RI values were significantly lower in patients with QR and RR alleles than in patients with QQ alleles (p=0.01). OTPR values at 5days maintenance dose of clopidogrel were similar across all the PON1 Q192R genotypes (p=0.41). PON1 192 QR and RR conferred increased risks for clopidogrel non-responsiveness [OR 3.64; 95% CI (1.21-10.92), p=0.02]. For CYP2C19*2 genotypes, compared to CYP2C19*1/*1 wild type carriers, CYP2C19*2 carriers showed a significantly higher OTPR (p=0.009), and a trend for lower RI values (p=0.06). An increased risk for clopidogrel non-responsiveness was found in patients with CYP2C19*2 genotype [OR 2.02; 95% CI (1.03-3.96), p=0.04]. CONCLUSIONS Both PON1 Q192R and CYP2C19*2 genotypes influence clopidogrel responsiveness, with the impact of PON1 Q192R mainly on relative platelet inhibition instead of OTPR of clopidogrel.

A comparison of elderly and adult multiple organ dysfunction syndrome in the rat model

Multiple organ dysfunction syndrome (MODS) in the elderly is the most common cause of mortality in critically ill elderly patients, and it is different from MODS in the adult in clinic. Rare studies have been done on its pathogenesis and the comparison between adult and elderly MODS animal models. This work aimed at exploring the mechanisms mediating elderly MODS and compared this with adult MODS. Male Sprague-Dawley aged and adult rats were intraperitoneally injected with zymosan for incitement of MODS. Aged rats receiving zymosan showed severer pulmonary, cardiac and renal dysfunctions than adult rats. Likewise, the tissue lesions under light microscope in major organs of zymosan treated aged rats were much worse than those of zymosan treated adult rats. Moreover, zymosan treated aged rats showed 142% and 64% greater increase in pulmonary alveolar macrophages (AMs) apoptotic rate and serum TNF-alpha level, respectively, whereas 43% smaller increase in serum IL-10 level compared to zymosan treated adult rats. Furthermore, lung injury was much worse than that in other organs in zymosan treated aged rats. Overall, these results suggest that zymosan can be used in aged rats to incite MODS in the elderly. In the animal model of elderly MODS, there are (1) severer injury in lung, heart and kidney vs adult; (2) easier to develop severe systemic inflammatory response syndrome (SIRS) instead of compensatory anti-inflammatory response syndrome (CARS) compared to the adult; and (3) severer inflammation in lung than other organs indicative of the possible roles of lung in triggering MODS in the elderly.

Mitochondrial tRNA mutations in Chinese hypertensive individuals.

PURPOSE Hypertension is a very important risk factor for cardiac vascular disease. The previous studies showed that mitochondrial DNA mutations are associated with cardiovascular disease, including hypertension. METHODS In this study we did systematical analysis on the total 22 mitochondrial tRNAs and the clinical, genetic and molecular changes of 140 Chinese hypertension and 124 controls. RESULTS This analysis identified 22 nucleotide changes among 15 different tRNA genes. There are 15 mutations with CI (Conservation index) larger than 75%. Of these, there are 26 patients with CI larger than 75% in the HTN group, higher than the 6 subjects in the control group (P=0.00). The tRNA(Phe) G586A, tRNA(Lys) G8313A and tRNA(His) G12147A mutations create highly conservative base-pairings on the D-stem, tRNA(Lys) G8342A on the T-stem, tRNA(Phe) T616C, tRNA(Ala) T5628C, tRNA(Tyr) G5856A and tRNA(Thr) A15924G on the AC stem, tRNA(Leu(CUN)) G12300A on the AC loop, tRNA(Met) C4467T, tRNA(Trp) T5578C, tRNA(Lys) A8296G, tRNA(Arg) T10463C and tRNA(Thr) C15891T on ACC stem, and tRNA(Ser(UCN)) C7492T on D-A junction, while the other tRNA variants were polymorphisms. The pedigrees of PLAH78 carrying the T5578C, PLAH84 carrying the C4467T, PLAH60 carrying the T5628C and PLAH118 carrying the C7492T mutation exhibited maternal transmission of essential hypertension. Sequence analysis of their mitochondrial genomes revealed the presence of T5578C, C4467T, T5628C or C7492T mutations but the absence of other functionally significant mutations in all matrilineal relatives of these families. CONCLUSIONS These tRNAs mutations, associated with altered structures of tRNAs and mitochondrial dysfunction, may contribute to the hypertension in Chinese population. A lot of work still should be done for the mechanism and functional effect of the mtDNA mutation on hypertension.

CYP4F2 polymorphism as a genetic risk factor for major hemorrhagic complications in Chinese patients on warfarin therapy

Warfarin is a commonly used anticoagulant with a narrow therapeutic range and risk of hemorrhagic complications. After CYP2C9 and VKORC1, CYP4F2 was confirmed as the third principle genetic determinant of warfarin dose variability. CYP4F2 functions as a vitamin K1 (VK1) oxidase, a counterpart to vitamin K oxidize reductase (encoded by VKORC1) in limiting excessive accumulation of VK1 in vitamin K cycle. Genotypes of CYP2C9 and VKORC1 are associate with increased risk of over anticoagulation or bleeding events during warfarin therapy. However, little is known about the influence of CYP4F2. Herein we present the association of CYP4F2 polymorphism and risk of major hemorrhage in Chinese patients on warfarin. HapMap Data (Phase III/Rel#2, Feb09, on NCBI B36 assembly, dbSNP b126) covering 50 kb length centered on CYP4F2 for Chinese was downloaded (http://hapmap.ncbi. nlm.nih.gov/). Haplotype blocks were constructed using Haploview version 4.2 software. The tag SNPs were selected with an LOD score cutoff of 3.0 and r threshold of 0.80. We genotyped eight tag SNPs (rs7251296, rs4808394, rs12610962, rs3093168, rs2074901, rs2018454, rs1558139 and rs3093200) in CYP4F2 using the multiplexed PCR-based SNaPshot system (Applied Biosystems) in 312 Han Chinese patients on warfarin. Three genetic determinants of warfarin dose, CYP2C9*3, VKORC1 -1639 G>A, and CYP4F2 V433M were also genotyped. Among the genotyped 312 patients (mean age, 56.6 ± 16.0 years; 50.6% men) on warfarin with